Segment LCD can display Arabic numbers represented by 7 segments or Arabic numbers and Roman letters represented by 14 segments. Symbols, such as plus/minus signs, measurement units and any custom icons, can also be displayed. Each symbol is treated as one segment.

Segment LCD is widely used on the displays of scientific instruments. It is easy to control and most cost-effective to develop.

Segment LCD is limited to displaying numbers, Roman letters and fixed symbols. If you need to display anything else, you have to use either the dot matrix display or graphic display.

Dot Matrix LCD (or Character LCD)

Dot matrix LCD is used to display a number of lines of characters. The most commonly used dot matrix LCD displays 1 to 4 lines of 16 to 40 characters. Each character is represented by 5x7 dots plus cursor (actually 5x8 dots including the cursor). Each character block is addressed separately and can form numbers, Roman letters, character in other languages and a limited number of symbols.

Dot matrix LCD is used when you need to display more characters than those in English alphabet. It is relatively simple to control and also inexpensive than graphic models.

Graphic LCD

Graphic LCD provides users with a greater degree of flexibility. They are composed of pixels arranged in rows and columns. Each pixel can be addressed individually for text, graphics or any combination of the two.

Graphic LCD is used in applications when the use need to have total control of the whole viewing area. However, flexibility also comes with the difficulty in designing the control circuitry. Fortunately there are special controller chips available for this purpose.